Phonograph pick up



Nov. 14, 1933.

w. H. HuT'n-:R 1,934,857

PHONOGRAPH PICK-UP Filed Oct. 13, 1930 3 Sheets-Sheet l Nov. 14, 1933.

W. H. HUTTER PHoNoGaAPH PICK-UP Filed Oct. 13', 1930 y 3 Sheets-Sheet 2Nov. 14, 1933. w H. HUTTER 1,934,857

PHONOGRAPH PICK-UP Filed 001.. l5, 1930 3 Sheets-Sheet 3 Patented'Nov.14, 1933' Y vPHONOGRAPH PICK William YllI. l Hu'tter, Racine,A Wis.,assignor to Webster Electric Company, -Racine, Wis., a .fcorporationofWisconsin Y' n; Application'Qctober 13, V1930. Serial No. 488,243 I sClaims.- (Cl.-1797100.41)

This inventionrelates-in general to reproducing devices or p'honographsand has more particular reference to a phonograph pickup for translatingmechanical movements into electrical impulses which may subsequently beVreproduced by the phonograph. w v

A primarypbject of thenvention is the .provisionof an improvedphonograph pickup or translating device for use in sound reproducingdevices f110- or phonographs- An important object ofy the invention isthe provision of such a phonograph pickup ortranslating device includinga generating assembly havf ing an adjustable gap between the pole piecesand 15, the armature.

Another important object ofthe present' invention is the provision of anovel rphonograph pick-V up having a vibratorymember so pivoted betweenmagneticpole pieces that the movement of said 29 member isaccuratelyandeflicientlyvconverted which are so designed, and lassembled that the1 mean magnetic path will beofjminimum length. Y

A further important object ofthe present invention is the provision ofazyoke assembly for electrical phonograph pickupswhich is'piovided withpolepieces of such shape as to provide a fulcrum for cam levers `movablysecured to the pole pieces and adapted to adjust resilient members lcarried by the pole pieces whereby to adjust the pressure on thearmaturearranged.betWeensad pole pieces. A i f' OtherA objects andVadvantages will appear'more fully from the following description andfrom the accompanyingdrawings, in which similar characters ofreferenceindicate similar parts throughout the. several views. j. f' y tIn thedrawingsz-l Y Fig. 1 is a side view of ar phonograph pickup ortranslating device embodyingfeatures. of the iniy 'vention; f Y Fig. 2is afront elevation ofthe phonograph pickup shown in Fig. 1-, withpartsbrokenr away;

Fig. 3 is a longitudinal-'section taken substantiallyon the line 3-,3 ofFig. 2 ;y Fig.- 4 is a horizontal section taken substantially on theline 4 4 ci Fig. 3;

Fig. 5 is a section taken substantially onthe line 5,-5 of Fig. 3;V f IFig. 6 a sectionftaken substantially on Vthe line-6 6 of Fig.4; 4.

Ya pivotal mountingfor'a vibratory member or Fig.- 7 is an enlargedperspective view of a lever member for adjusting the pressure on thearmature of the phonograph pickup shown-in Fig. 8 is an enlargedperspective view of a portion Vof the yoke employed in the translatingdevice of the invention-and Vshows certain assembly details; Y

Fig. 9 is an enlarged perspective Yviewof the vibratory member employedinthe translating device oi the invention; Y

Fig. 1 0 is a perspective viewrof a portion of the yoke employed tobridge the magnet of the novel phonograph pickup,vand

--Fig. 11 is aperspective view oi a resilient mem- 70.

c ber used to mountv thearmature of Fig. 9.v i

The present invention contemplates briefiy an improved translatingdevice or phonograph pickup of the electrofmagnetic type which isprovided with a YyokeA surrounding .and carrying a generator coil andextending between or bridging the poles of amagnet. This yoke comprisespole pieces carrying non-magnetic members for adjustably spacing thepole pieces and for vproviding armature extending through the coil tovary the gap between the pole pieces at the opposite sides of the coil;the pivotal axis of the armature be ing between the two gaps at theopposite ends of thecoiLf r85 Thisfvibratory member or armature isactuated .bythe stylus or needle of the phonograph in playg V'ing' afrecord and reciprocates between the pole vpieces atthe-oppositesides ofthe coil. This vibrationor reciprocation ofY the armature Variesthereluctance of the magnetic vcircuit whichY inducesfV a "current l inthe generator coil correlated .to the "mechanical movements of Ltheneedle or I stylus fproduced'by therecord. These variations in` currentmay beamplied and'converted into 95 soundwaves in a wellknownmanner.

To accomplish the foregoing objects a casing 1 5 comprising a base ormounting plate 16 and a cover member 17 is secured at an end of atubular Y arm ortone arm 1 8' by means of mounting-screws 19 andencloses a generating. assembly', generally designatedbythe reference`character 21. The casing maybe made of any suitable non-.magneticmaterial such as aluminiun.y

The generating assembly21 includes a U-shaped magnet 22,- preferably ofthe permanent magnet type .mounted on the base, plate 16 by means of astrap or tie plate 23and a screw 24 threading vintothe plate 16.` Thestrapj23 is provided with taining screw 25 threads to hold the covermember 17 to the plate 16. A magnetic yoke generally designated by thereference numeral 26 surrounding a generating 'coil 27 provides with thecoil a unitary assembly extending or bridging between the poles of themagnet 22. This unitary assembly is secured to the base plate 16 bymeans of through bolts or studs 28 and nuts 29 arranged at each end ofthe yoke 26 to hold it adjacent the poles of the magnet.

The coil 27 is illustrated, particularly in Figs. 1 and 5, as being or"greater diameter than the width of the yoke 26 and extends beyond theyoke laterally into a recess 3l provided. in thevbase plate`16 for thatpurpose. A terminal block or strip 32 is mounted on a stud 33 integralwith the base plate 16 by means of a screw 34.*and carries a pluralityof terminals 35'connected to the coil 27 by conductors 36. The terminals8,5 may be connected by conductors 37 in the tubular arm 18 to asuitable amplifying device the output of which is converted into soundwaves'.

Thelmagnetic yoke 26 Vis constructed and assembled as shown in Figs. 5and 8 to provide magnetic pole pieces 38 and 89 which are substantiallyU-shaped to accommodate the coil 27 and to provide a mean magnetic pathof minimum length. The pole piece 38 comprises a side member 41 spacedapart from a side member 42, the side members 41 and 42 being connectedby an integral end piece 43 to provide a short magnetic path between theside members which extend therefrom at a pole of the magnet 22 tosubstantiallycentrally of`r the coil 27, the side members 41 and 42being reduced in width to provide pole tips 44 and 45respectively atopposite ends of the coil, and a shoulder 46. In like manner the polepiece 39-is providedfwith side members 47 and 48 kand an integral endpiece 49. 'These side members are constructed with pole tips 51 and 52and shoulder-53 respectively corresponding to the pole tips 44 and' 45and the shoulder 46. y f

Non-magnetic members 54, shown more particularly in Figs. 8 and 19 ofany suitable shape such as channel-shaped, are formed withspaced sides55 which are receivable in alignedslots 56 in opposite sides of the polepieces A38 and 39 to hold the pole pieces in such an' adjustableposition as to provide a small adjustable space or gap between pole tips44 and 51 and a larger adjustable gap or space between pole tips 45 and52. The screws 28, passing through aligned slots 57 at each end of eachmember 54 and the holes 58 and 59 in the pole pieces 38 and 39respectively hold the yoke assembly in assembled relation adjacent thepoles of the magnet 22.V The slots 57 at the ends of thenon-magneticmembers 54` extend longitudinally of.` the members 54 and permitadjustment of the pole pieces to vary the distance or gap betweenpole-tips44 and 51 and the gap between pole tips A45 and52 to adapt thegenerating unit to various magnetic and playing conditions.

The face of each'channel member`54 is cut away or apertured as' at 61 toaccommodate the coil 27 having a larger diameter than the width of thepole pieces. These channel members serve as a mounting for a vibratorymember or armaor spring 65 having a knife edge 66 which engages a side67 of an aperture 68 in the armature tips 45`and 52 and to permit theadjustment of the pole pieces 38 and 89. The coil has its end 72 groovedas at 73 to accommodate the grooved portions of channelvmembers 54 forthis purpose.

At one end of the armature 62, a rectangular projection or lug 74extends beyond the sides of the pole-pieces l38 and '39 and is providedWith a bushing 75 to separate the armature from the cover member 17.This projection registers with a slot or opening 76 in the cover memberthrough which-,a needle or stylus 77, held therein by a retaining screw78, projects forengaging and playing a record.Y This.k end ofthearmature. substantially lls the larger. gapbetween the pole tips r45and 52. The other end of the. armature is reduced in thickness as at 79andfis4 adapted .to reciprocate between lpole tips-44.and.51 .as-.thearmature vibrates orreciprocates about its pivot.

The grooves 64 in the channelmembers; 54 are located midway between thepole pieces 88 and 39 and have a depth sufficient to establish the axisof the pivot of the armature between the gaps formed by the pairs ofspaced pole tips. This' arrangement of the armature pivot between the.air gaps and theconstruction of pole Apieces 38 and 39 to provide shortmagnetic paths magnet.

The reluctance of the air gaps between the reduced end of thearmatureand the pole tips 44and 51 and between theopposite end of thearmature and the pole tips 45 and 52 will vary as the armature vibrates.As the end 79 of the armature approaches nearer the pole tip 44, thereluctancethroughthis pole tip, armature 62, and the pole tip, 52 willbe decreased and the reluctance through-the pole tip 45, armature 62,and the pole tip 51, will increase, thereby permitting themagneto-motive force of the magnet to impress a flux upwardly throughthe. armature Vas Viewed in Fig. 5. A flux having a direction downwardlythrough the armature is set up in the magnetic Vcircuit as the armaturemoves in the opposite direction. This vibration of the armatureproducesacorresponding variation in the flux in the armature, whichinduces a current in the coil 27, the wave form of which bears a deniterelation to the vibrations of the armatureor -the' needle 77 carriedthereby.

Thus pole pieces 38 and 39, the coil 27,'and the 14 armature -62 vareassembled as a unit by means of the channel shaped members 54-and theresilient member-65 which pivotally support the armature on an axisbetween the gaps formed` by the pole pieces. This unit may bemounted onthe plate 16 by the studs 28' and Vthel nuts 29 for testing and removedforadjustment of the gaps between the pole tips and' the'v armature.These gaps between the poletips andthe armature at opposite ends of thecoilv27 are adjust- 150 pieces along the channel sidesjvengaging'fin softhe-slots 56 of the pole ipieces.' v.Whenthe gaps have-been adjustedtosuit the magnetic circuitv and to provide a desired tone'or to suit anyvdesired magnetic or playing. condition .the screws 71 may be Vtightenedand the .unit again mounted on the plate 16 by the studs 28and thenuts29. The `knife edge support-for the armature 62 makes an efficientdamping means possible for the armature and thereby `permits the use ofthe resilient member to provide a yieldable and substantially motionlessbearing for the armature of this novel adjustable unit or yoke. Thisdamping of the armature 62 isaccomplished by resilient material 82 inslots 81 which are vformed in the adjacent ends of the pole tips 44 and5l by a round tool to provide a circular section whereby to prevent the'resilient material 82 from working out sidewise. This resilientmaterial 82 engages the free end 79 of the armature to maintain thearmature in the normal position centrally of the gap between the poletips 44 and 51.

Each side member 41 and 47 carries a lever 83, see Fig. 7, having ahandle 84 accessible when the cover member -17 is'removed to adjust thepressure-exerted against the armature by the resilient material 82.These levers 83 are carried on the pole pieces v38 and 39 by mountingscrews 85 engaged by cam slots 86 for guiding a I dependingfinger or lug87 extendinginto each slot 81 for engagement with the resilient material82, to vary the pressure exerted Vthereby against the end 79-of1 thearmature. The movement of the lever 83 Yis accomplished about adepending lug 88 fulcruming against the shoulders 46 and 53. y

VThe pole tips 44 and51 attract the armature in accordance with itsproximity to a vpole tip, but the resilient material82 applies a forcetending to return the armature 62 to its central position, which alsoincreases; with the proximity of the armature to a pole tip so that themagnetic attraction ofthe larmature is counterbalanced by the resilientmaterial and therefore willl not eifect the movement of the armature.'

In operation the stylus or needle is vibrated in playing a record. Thisvibration of the stylusr is transferred or communicated to Ythe armature62, causing the reduced end '79 to reciprocate vbetween the pole tips 44and 51 andthe lother end ofthe armature to reciprocate between pole tips45 and 52. The magnet 22 sets up a magneto-motive force between the polepieces -38 and 39. The ilux rproduced by this magnetomotive force isreversed in ydirection each time the reduced end 79 of the armaturepasses its central position, thereby inducing a current in the coil 27,correlated to the 4movement yof the armature G2 or the'needle'T7/.carried thereby. This current may then be `amplified and convertedinto sound by any'suit'able means; i

A feature of the present invention is the -adjustable air gapsbetweenth'e pairs of.l pole tipsV whereby to vary the reluctance of themagnetic circuits for magnets having variable or differentmagneto-motive forces, and for ampliers or phonographs having differentcharacteristics.

While I have illustrated and described a specic embodiment of myinvention, many modications may be made without departingV from thespirit of the invention, and `I do not wish to f be limited to theprecise details set forth but f desireto -avail myself iof all changeswithin the scopeofgthe appendedclaims l Y Y. VLHavingjthus'fdescribed myinvention, what I claimv-is/,new and desire tosecure by Letters Patentof the vUnited Statesis: Y I

1. YAA phonograph pickup comprising a magnet p having adjustably spacedlpole piecesprovided with corresponding slots extendinglongitudinally ofsaid pole pieces, a coil carried by said .pole pieces, a movablearmature passing through rsaid coil and between said pole pieces,rand amount-` ing means for said armature carried in said corresponding slots.

. 2. A phonograph pickup comprising a magnet having Vadjacently disposedpole pieces pro-f ided with corresponding slotsat opposite sides of saidpole pieces, a coil carried by said polev pieces, non-magnetic membersslidably arranged in said slots and bridging between said pole ,v

pieces, and a `movable armature betweenv said pole Vpieces pivotallyengaging said members at one side of said coil, and having a portionextending through said coil whereby to provide unequal variations in themagnetic reluctance between said armature and said pole pieces at op-`posite sides of said coil.

3. A phonograph pickup comprising a magnet,

a coil, a yoke bridging the ends of the magnet and surrounding the coil,said yoke including a pair of adjustable pole pieces having a pluralityof aligned slots, and a plurality of non-magnetic` members engaging insaid slots and holding the ends of said pole pieces in spaced relation,and a vibratory armature pivotally mounted on the non-magnetic membersinwardly ofthe surface ofthe pole piecesVV on one side of said coil' andextending into the gap between the pole pieces on the other side'of saidcoilwhereby to induce a currentin said coil.

responding sidesa'pair of U-shaped magnetic members having aligned slotscarrying said non-y magnetic members, said magnetic members beingv heldin` adjustable spaced relation thereby and extending from centrally ofthe coil over Ythe lateral sides of said coil to centrally of the otherside -of said coil, and providing adjustable gaps between the ends ofsaid magnetic members, and an'A armature having av knife edge supportcar'- U riedfin the aligned grooves of said non-magnetic membersbetweensaid gaps, said armature-extending through said coil andvhaving its endsreciprocable in said gaps.

6. A phonographpickup comprising' a 'coiL-aV pair of pole pieces ateachend of said coil having gaps therebetween, a magnet associated with saidpolepieces, an armature extending through the gaps between the polepieces and having a plurality of knife edges a plurality Vof channelmembers having grooves therein carrying said armature and said polepieces, the pivot point of said armature being between the pairs of.pole pieces at-the end of said-coil, said pole pieces lbeing adjustablewith respect to said'channel members to adjust the gap between said polepieces, and means for moving the` armature about its pivot to generatefacurrent in said coil. f

'7;v A- phonograph pickup comprising` a magnet and a unitary generatingassembly bridging between the poles of said magnet and including aeoiLcOmplementary bifurcated pole pieces adjustably assembled about saidcoil and a dampened vibratory member having a pivotal mount-

